Browsing by Author "Huang, Cheng-Ting"

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Hybrid light field head-mounted display using time-multiplexed liquid crystal lens array for resolution enhancement
(2019-01-21)
Chou, Ping-Yen
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Wu, Dui-Yi
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Huang, Shang-Hao
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Wang, Chun-Ping
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Qin, Zong
In recent years, head-mounted display technologies have greatly advanced. In order to overcome the accommodation-convergence conflict, light field displays reconstruct three-dimensional (3D) images with a focusing cue but sacrifice resolution. In this paper, a hybrid head-mounted display system that is based on a liquid crystal microlens array is proposed. By using a time-multiplexed method, the display signals can be divided into light field and two-dimensional (2D) modes to show comfortable 3D images with high resolution compensated by the 2D image. According to the experimental results, the prototype supports a 12.28 ppd resolution in the diagonal direction, which reaches 82% of the traditional virtual reality (VR) head-mounted display (HMD). (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Image formation modeling and analysis of near-eye light field displays
(2019-04-01)
Qin, Zong
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Chou, Ping-Yen
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Wu, Jui-Yi
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Chen, Yu-Ting
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Huang, Cheng-Ting
Near-eye light field displays based on integral imaging through a microlens array provide attractive features like ultra-compact volume and freedom of the vergence-accommodation conflict to head-mounted displays with virtual or augmented reality functions. To enable optimal design and analysis of such systems, it is desirable to have a physical model that incorporates all factors that affect the image formation, including diffraction, aberration, defocusing, and pixel size. Therefore, in this study, using the fundamental Huygens-Fresnel principle and the Arizona eye model with adjustable accommodation, we develop an image formation model that can numerically calculate the retinal light field image with near-perfect accuracy, and experimentally verify it with a prototype system. Next, based on this model, the visual resolution is analyzed for different field of views (FOVs). As a result, a rapid resolution decay with respect to FOV caused by off-axis aberration is demonstrated. Finally, resolution variations as a function of image depth are analyzed based on systems with different central depth planes. Significantly, the resolution decay is revealed to plateau when the image depth is large enough, which is different from real-image type light field displays.
Improved Electric Properties of Degraded Liquid Crystal Using Metal-Organic Frameworks
(2013-12-01)
Huang, Cheng-Ting
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Liao, Kun-Ting
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Lin, Chia-Her
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Hsu, Jy-Shan
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Lee, Wei
A series of experiments are conducted to examine the purification effect on degraded liquid crystal (LC) by soaking porous metal-organic frameworks in the LC material. The results indicate that the electric properties of the degraded LC are dramatically improved due to the adsorption and removal of moisture and impurity ions, most likely originating from the atmosphere. This investigation leads to the advancement in the feasible recycling of deteriorated LC materials, including LC leftovers from flat-panel production lines, with a simple and cost-effective treatment method. (C) 2013 The Japan Society of Applied Physics
Long working range light field microscope with fast scanning multifocal liquid crystal microlens array
(2018-04-16)
Hsieh, Po-Yuan
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Chou, Ping-Yen
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Lin, Hsiu-An
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Chu, Chao-Yu
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Huang, Cheng-Ting
The light field microscope has the potential of recording the all information of biological specimens in real time with a conventional light source. To further extend the depth of field to broaden its applications, in this paper, we proposed a multifocal high-resistance liquid crystal microlens array instead of the fixed microlens array. The developed multifocal liquid crystal microlens array can provide high quality point spread function in multiple focal lengths. By adjusting the focal length of the liquid crystal microlens array sequentially, the total working range of the light field microscope can be much extended. Furthermore, in our proposed system, the intermediate image was placed in the virtual image space of the microlens array, where the condition of the lenslets numerical aperture was considerably smaller. Consequently, a thin-cell-gap liquid crystal microlens array, with fast response time can be implemented for time-multiplexed scanning. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Metal-Organic Frameworks for Regeneration of Degraded Liquid Crystals
(2014-09-22)
Lee, Wei
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Huang, Cheng-Ting
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Liao, Kun-Ting
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Hsu, Jy-Shan
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Lin, Chia-Her
This paper is concerned with the dramatic purification effect of porous metal-organic frameworks (MOFs) and regeneration of a degraded liquid crystal (LC) as leftover from a flat-panel production line. By soaking MOFs in the LC, the correlation between the recovery of electrical properties and the water-sorption capacity of MOFs is unambiguously revealed. Experimental evidence from the data of voltage-dependent capacitance, dielectric spectroscopy and voltage holding ratio strongly suggests that the primary contaminant in a LC leftover is moisture. This investigation paves the way for feasible recycling of deteriorated LC materials. The approach reported in this study can be applied to many fluids for purification and regeneration.
Resolution-enhanced light field displays by recombining subpixels across elemental images
(2019-05-15)
Qin, Zong
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Chou, Ping-Yen
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Wu, Jui-Yi
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Huang, Cheng-Ting
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Huang, Yi-Pai
Light field displays based on integral imaging feature ultra-compact volume and freedom of the vergence-accommodation conflict for advanced virtual reality and augmented reality devices; however, they currently suffer from low visual resolution. Considering that subpixels have an intrinsically tripled resolution compared with triad pixels, this Letter develops a subpixel-level algorithm by recombining subpixels with relatively small raytracing errors from different elemental images. As a result, based on a highly accurate image formation model, the resolution of a typical system (pixel size, 7.8 mu m; system thickness, 4.07 mm) is remarkably enhanced from 8.3 to 20.0 pixels per degree, for a gain of 2.41. In addition, the color breakup introduced by the chromatic subpixels is largely suppressed. (C) 2019 Optical Society of America
Revelation and addressing of accommodation shifts in microlens array-based 3D near-eye light field displays
(2020-01-01)
Qin, Zong
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Wu, Jui-Yi
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Chou, Ping-Yen
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Chen, Yu-Ting
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Huang, Cheng-Ting
In a 3D near-eye light field display using microlens arraybased integral imaging, the accommodation response is presumed to exactly coincide with the reconstructed depth plane (RDP) which, however, has been little examined. By employing a highly accurate image formation model to analyze retinal images, the accommodation response is revealed to significantly shift towards the central depth plane (CDP) because of defocusing. The shift is quantitatively characterized for various CDPs and RDPs with a preliminary verifying experiment to provide content producers an approach to address the accommodation shift to fully mitigate the vergence-accommodation conflict. (C) 2019 Optical Society of America